The microvascular footprint of lupus: nailfold capillaroscopy findings in Egyptian SLE patients and their link to disease activity, autoantibodies, and digital ischemia.

BACKGROUND: Microvascular injury is central in systemic lupus erythematosus (SLE), and nailfold capillaroscopy (NFC) can noninvasively visualize this damage, but data in Egyptian patients are limited. OBJECTIVES: To characterize NFC patterns in Egyptian SLE versus healthy controls, and to relate capillaroscopic abnormalities to disease activity and major clinical/serologic features. METHODS: In a case-control, cross-sectional study, 106 adult SLE patients and 106 age- and sex-matched controls from two Egyptian tertiary centers underwent standardized NFC (× 200) of eight fingers. Quantitative (density and loop width) and qualitative (morphology, hemorrhages, avascular areas, neoangiogenesis, architecture) parameters were recorded. Associations with disease activity, autoantibodies and digital ischemic lesions were analyzed. RESULTS: Capillary density was reduced in SLE versus controls (median 8 vs. 9 loops/mm; p < 0.001), with greater loop width (21 vs. 15 µm; p < 0.001). Tortuous (68.9% vs. 16.0%) and branched capillaries (12.3% vs 0%) were more frequent in SLE (all p <  < 0.001), as were enlarged/giant capillaries and microhemorrhages (p ≤ 0.004); disturbed architecture, avascular areas, and neoangiogenesis were largely confined to SLE, and subpapillary plexus visibility was higher (45.3% vs 26.4%; p = 0.002). Higher disease activity correlated with lower density (r = -0.309, p = 0.002), more microhemorrhages (r = 0.470, p = 0.001), avascular areas (p = 0.002), and neoangiogenesis (2.4% vs 8% vs. 35.7% across mild, moderate, and severe; p = 0.001). Anti-dsDNA and antiphospholipid antibodies were associated with lower density (r = -0.261, p = 0.024; r = -0.273, p = 0.005) and more microhemorrhages (r = 0.249, p = 0.035; r = 0.510, p = 0.001); digital ulcers correlated strongly with microhemorrhages (r = 0.476, p < 0.001). CONCLUSION: Egyptian SLE patients exhibit characteristic NFC abnormalities that correlate with disease activity, autoantibody profiles, and digital ischemia, supporting NFC as a potential adjunct for risk stratification and monitoring in this population. Key Points • Compared with healthy controls, Egyptian SLE patients showed widespread nailfold capillary changes affecting density, morphology, and vascular architecture, confirming that microvascular injury is a consistent feature of the disease in this population. • The extent of capillary damage paralleled SLE disease activity, with more pronounced abnormalities, including lower capillary density and greater microhemorrhages, avascular areas, and neoangiogenesis, seen in patients with higher disease activity. • Capillaroscopic abnormalities also tracked with autoantibody status and digital ischemic disease, linking anti-dsDNA and antiphospholipid antibodies, as well as Raynaud's phenomenon and digital ulcers, to greater microvascular injury. • The study highlights nailfold capillaroscopy as a low-cost, non-invasive adjunct for assessment of Egyptian SLE patients, reflecting both inflammatory and thrombotic microvascular injury. Its cross-sectional associations with disease activity suggest potential utility for monitoring.